Apparatus employing cavity resonators



July 13, 1948. L. s. NERGAARD APPARATUS EMPLOYING CAVITY RESONATORS Filed July 28, 1944 I l l I I I l I Il` f imm? :inventor Waard Gtforneg Patented July 13, 1948 ArrAitA'rUs EMPLOYING cAviTY v REsoNA'roas k 1 Leon S. 'NergaartL Princeton;

vRadio Corporation of America,

Delaware N. I.1.,yassgnor to a corporation of Application July 2s, 1944, serial No. 547,010

be accomplished'if.the resonator can be `made small enough. However with the construction shown'in tilleabove-identified application it is;

dfcult toaccomplish this modeof operation.

Itis, therefore, an object of my present invention to provide an electron discharge device and associated circuit of: the cavity resonator type in which the cathodefgrid resonator or input resonator may be operated in the fundamental mode.

More specically it is an `object of my invention to sov design the cathode-:grid cavity resonator which will permit tuning and fundamental mode yoperation without changing vthe designof thetube described in theabove-mentioned application.. i

i l'Ihenovel features 'which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which Figure 1 is a longitudinal Isection of an electron discharge device and associated circuit made according to my invention and now Patent No. 2,341,273, granted November 18, 1947, and Figure 2 is a longitudinal section of a modification of the electron discharge device and circuit shown in Figure 1.

In Figure 1 I describe an electron discharge device comprising an indirectly heated cupshaped cathode 2|] nested within the grid I9 and anode I2 provided with the cooling fins I3. The anode is provided with the collar I4 sealed to insulating collar member I5 which in turn is sealed to a second collar I5 by `which the grid I9 is supported. This collar is provided with a transverse flange 21, The cathode electrode is insulatingly supported from the base of the tube and sealed through the collar I1. The cathode leads I8 extend through the collar member I1.

The output cavity resonator is of the half -wave type and comprises inner conductor 2| secured to the anode and an outer conductor 22 having an aperture 24 surrounded by the outer conductor 24 3 Claims: (Cl. 315-39) ofa.y coaxial line, and through which extends the inner conductor conductor` 23 is capacitively coupled to the line 2 I Voltage is applied to the anode at a voltage node by means'of voonductc'ir 26 extending through aperture 25. The flange 21 is clamped to the plate 22 closing the lower end of the outer coaxial conductor y22 by means of radially slidable segmentally shaped clamps bers 29.

In order to operate in the input cavity resonator must be made as small as possible. According to my invention I utilize the cathode pins I'B'as the inner conductor of a. transmission line. The plate 22' carries conducting collar 3u coaxial with and extending parallel to the cathode pins I8. Mounted between the pins I8 and the collar3|| is a sliding sIhort circuit ca pacity device comprising van outer ring 3| having spring fingers 3| and an inner ring 32 hav- 'lngI spring fingers 32', these rings being insulatingly separated from each other by'means of' the insulating collar 34 vpreferably of mica. This shorting condenser may be positioned so that the pins I8 and collar 30 act as vthe inner and. outer conductors of a coaxial line cavity resonator' b e-` tween the cathode and grid. The compact arrangement described will thus function at a very high frequency in a fundamental mode. Feedback may be provided by t'he cathode-anode capacity within the tube.

In the modification shown in Figure 2 like members designate like parts as in Figure 1. In this arrangement, however, the anode is provided with a flange 2|, capacity coupled to the flange 2| through the insulating collar 30, preferably of mica. The output cavity resonator comprises the cylindrical member 3| closed at vits bottom by means of the plate a cavity resonator formed by elements 2|, 3| and 32. 'Ilhe anode is insulated for direct voltages and currents. The grid flange 21 is clamped in a manner similar to that in Figure 1.

The input cavity resonator in the arrangement shown in Figure 2 includes the collar 33 between which and the cathode pins I'B is mounted a modified form of short circuiting condenser including outer ring 34 and inner ring 35 insulatin'gly separated by means of the mica collar 36. Adjusting means for the short circuiting condenser includes the extensions 31 and 31 on outer Aring 34. The extensions are threaded to receive adjusting screws 38 vand 39 rotatably supported by the plate 32 which is recessed to 23 of the coaxial line. The innerl 28 which may be fixed in position by means of the screw mem-k a fundamental mode 32. Thus there is. provided the use indicated, but that many variations may,

be made in the particular structure used and and the inside of said collar, and including a pair of coaxial conducting rings mounted in insulated spaced relationship, said collar having oppositely disposed Islots extending from one end normal to said flange, means secured to said condenser land including a pair of oppositely disposed arms extending through said slots parallel to said flange and means including screw means rotatably secured to said flange and extending to tune said second cavity resonator.

the purpose for which it is employed without de-f' parting from the scope of my inventionas set forth in the appended claims.

What I claim as new is:

1. An electron discharge device having an anode, a grid and a cathode, said grid having Va radially Idirected flat conducting member con nected therewith, said cathode having terminals,

extending normal to .the plane of rand through said conducting member, a collar :having one end connected vto said conducting member and surrounding said terminals and coaxial with said terminals, and a rst means including anv inner and outer conducting ring having resilientfingers thereon contacting said terminals and said collar, said rings. being secured together insulatingly from each other bymean-s of an insulating collar, said terminals, collar and means providing a resonator, and a second means for adjusting said first means longitudinally of said collar and terminals and including a screw means supported adjacent said collar, and ymeans extending between said rings and said screw means whereby said first means may be adjusted longitudinally.

2. An electron discharge device havingl an anode, a grid and a cathode, lsaid grid being provided with a flange transverse to the longitudinal axis of said electron discharge, cathode terminal pins extending through and normal to the plane of the grid `:flange and positioned within a circle, and a cavity resonator` coupled between said anode and grid, and a second cavity resonator coupled between said grid and said pins and including a collar supported the iiangeV and a -vtuning condenser mounted on said pins for longitudinal movement and contacting said pins through said arms for adjusting said condenser 37;. An electron discharge'device having an anode, a` grid and a cathode, said grid being provided. with ka flange transverse to the longitudinal axis of said electron discharge, cathode terminal pins extending through the envelope i .j of. they tube and normal to the plane of the grid flange and positioned within a circle, and cavity resonatorv coupled between said anode and grid, and a second cavity resonator coupled between said grid and said pins and including a collar supported by the flange and a tuning condenser mounted on said pins for longitudinal movement, and including a pair of coaxial conducting rings having resilient ngers contacting said pins and the inside of said collar, and means insulatingly supporting said collars in spaced relationship, said collarhaving oppositely disposed slots extending from one end normal to said flange, means secured tosaid condenser and including a pair of oppositely disposed arms extending through said slots parallel to said flange and means including screw means rotatably secured to said flange and extending thru said arms for adjusting said condenser to tune said second cavity` resonator. l

LEON S. NERGAARD.

REFERENCES CITED The following references are of record in the lile of this patent:

UNITED STATES PATENTS McArthur July 18,l 1944 

